The physicochemical and immunologic properties and metabolism of the alpha-fetoproteins isolated from fetal/newborn rat serum and from the serum of adult rats bearing transplantable Morris hepatomas 7777 and 8994 and hepatomas induced by feeding 3'-methyl-4-dimethylaminoazobenzene will be studied, to elucidate the relationship between these proteins and to elucidate the controls of genetic expression in normal fetal and neoplastic tissues. Alpha-fetoproteins isolated by a method developed in this laboratory will be analyzed for carbohydrate and amino acid content, peptide fingerprints, N- and C-terminal amino acids, sedimentation constant, molecular weight, isoelectric point, quaternary structure, immunologic cross-reactivity and antigenic determinants. The metabolism of I131- and I125-labeled fetal rat alpha-fetoprotein and hepatoma-bearing adult rat alpha-fetoproteins will be compared in normal adult rats and in adult rats during the induction and tumor phases of hepatocarcinogenesis. These studies will reveal if fetal and tumor alpha-fetoproteins have similar, if different, metabolic patterns, and if alterations in the metabolism of alpha-fetoprotein occur during hepatocarcinogenesis. The significance of these studies will be to increase our understanding of gene expression in neoplastic and normal tissue.